Soldering of VCSEL arrays to a heat sink or a submount creates stress due to the CTE mismatch between the two components. This limits the maximum chip area that can be soldered with good reliability. Furthermore, the effort to align the VCSEL arrays to optical elements like micro lens arrays which may be needed to shape and collimate the beams of the VCSELs increases.
U.S. Pat. No. 7,792,173 B2 discloses a multi-beam semiconductor laser device in which relative difference in shear strain applied to each of light-emitting portions of a laser chip mounted on a submount is suppressed.
The effort of assembling the described multi-beam semiconductor laser device is still high.